The present invention relates to a system and method for using real-time broadcasts of traffic and road conditions in a navigation system, and more particularly, the present invention relates to a system and method that facilitates and implements the use and coordination of traffic broadcast data in a navigation system that uses a geographic database.
In some regional and metropolitan areas and countries, systems have been implemented that broadcast up-to-the-minute reports of traffic and road condition information. These systems broadcast traffic and road condition information on a continuous, periodic, or frequently occurring basis. These broadcasts can be received by receivers installed on-board vehicles that travel in the region. The on-board receivers decode the broadcast reports and make the information in the reports available to the vehicle driver.
These traffic report broadcast systems have several advantages over the simple broadcasting of traffic reports over radio stations. For example, with these traffic broadcasting systems, a driver can obtain the report more quickly. The driver does not have to wait until a radio station broadcasts a traffic report. Another advantage of these traffic broadcasting systems is that the driver does not have to listen to descriptions of traffic conditions for areas remote from his or her location. Another advantage of traffic broadcast systems is that more detailed and possibly more up-to-date information can be provided.
In these types of systems, the traffic information that is broadcast conforms to one or more pre-established specifications or formats. These specifications or formats are used by the on-board receivers in the vehicles that travel in the region to decode the traffic report messages.
One system for broadcasting real-time traffic and road conditions is the Radio Data System-Traffic Message Channel (“RDS-TMC”). The RDS-TMC system is used in some European countries. The RDS-TMC system is described in various publications, including “Radio Data System, CENELEC END50067:1996,Specification of the Radio Data System.” The RDS-TMC system broadcasts traffic messages to vehicles using an FM station data channel. RDS-TMC messages are broadcast regularly or at varying intervals depending on the priority of the events. Similar or identical systems are being used or are being planned in other countries and regions.
For purposes of identifying locations of traffic congestion, the traffic and road condition broadcast systems in use today, as well as those planned for the future, assign codes to locations in a covered region. For example, in the RDS-TMC system, location reference codes are assigned to specific locations along roads in a covered geographic region. The locations may be intersections, interchanges, or portions of roads. Then, data messages are broadcast identifying traffic conditions relating to these locations. In general, these locations relate to heavily traveled roads, such as expressways and main roads.
Another, separate technology that has developed to assist drivers is the vehicle navigation system. Vehicle navigation systems provide various navigating features to drivers of vehicles, as well as others. The features provided by a vehicle navigation system differ from those provided by a traffic broadcast system. For example, a navigation system can calculate a specific route for a driver. The route calculated for the driver can begin at any street location in a covered geographic area and have a destination located at any other street location in the covered geographic region. The vehicle navigation system may also provide route guidance to the driver. The route guidance function can also be specific to the route calculated for the driver. The route guidance function may provide maneuvering instructions, audibly or visually, to the driver as the route is being followed. The navigation system may also provide other features, such as finding one or more destinations of a particular type within a given search area, such as all the Italian restaurants within two miles of a present position of the vehicle. In order to provide these kinds of functions, the navigation system uses a detailed geographic database, either located in the vehicle or accessible over a wireless communication link.
Both traffic broadcast systems and navigation systems can provide drivers with valuable features. However, even additional useful features could be provided if the data in the traffic broadcast reports could be used in conjunction with the navigation system features. For example, it would be advantageous if the data in the traffic messages could be utilized when calculating a route using the route calculation function in the navigation system. Unfortunately, the data in the reports broadcast by traffic broadcast systems, such as the RDS-TMC system, do not relate to the data used by the navigation system. For example, the location numbers assigned by the traffic broadcast system authorities, do not directly relate to any physical feature represented by the data records in the geographic database used by a navigation system.
Accordingly, there exists a need for using broadcast traffic reports in conjunction with a vehicle navigation system that uses a geographic database.